Aligned dipolar molecules, incorporated into the interface between a membrane and an adjacent aqueous phase, will introduce a dipolar component to the overall variation of electrostatic potential across the interface. This dipole potential can be detected by use of hydrophobic ions as probes. We propose to use such probes to evaluate dipole potentials produced by boron-nitrogen compounds. We will employ a range of compounds having differing separation between N plus and B minus charge centers, and also having differing distributions of hydrophilic and hydrophobic groups relative to these centers. In this way it should be possible to relate these structural factors to the sign and magnitude of the observed dipole field.